Date: Tue, 14 Apr 2015 10:24:38 +0200
From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, linux-kernel@vger.kernel.org,
        Pawel Moll <pawel.moll@arm.com>, virtio-dev@lists.oasis-open.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v3 0/6] virtio_balloon: virtio 1 support
Message-ID: <20150414102438.11d12347.cornelia.huck@de.ibm.com>
In-Reply-To: <87h9sjtsvb.fsf@rustcorp.com.au>
References: <1427884468-23930-1-git-send-email-mst@redhat.com>
	<20150412170141-mutt-send-email-mst@redhat.com>
	<87h9sjtsvb.fsf@rustcorp.com.au>
Organization: IBM Deutschland Research & Development GmbH Vorsitzende des
 Aufsichtsrats: Martina Koederitz =?UTF-8?B?R2VzY2jDpGZ0c2bDvGhydW5nOg==?=
 Dirk Wittkopp Sitz der Gesellschaft: =?UTF-8?B?QsO2Ymxpbmdlbg==?=
 Registergericht: Amtsgericht Stuttgart, HRB 243294
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1967
Lines: 40

On Tue, 14 Apr 2015 10:42:56 +0930
Rusty Russell <rusty@rustcorp.com.au> wrote:

> "Michael S. Tsirkin" <mst@redhat.com> writes:
> > On Wed, Apr 01, 2015 at 02:57:35PM +0200, Michael S. Tsirkin wrote:
> >> Virtio 1.0 doesn't include a modern balloon device.  At some point we'll likely
> >> define an incompatible interface with a different ID and different
> >> semantics.  But for now, it's not a big effort to support a transitional
> >> balloon device: this has the advantage of supporting existing drivers,
> >> transparently, as well as transports that don't allow mixing virtio 0 and
> >> virtio 1 devices. And balloon is an easy device to test, so it's also useful
> >> for people to test virtio core handling of transitional devices.
> >> 
> >> The only interface issue is with the stats buffer, which has misaligned
> >> fields. We could leave it as is, but this sets a bad precedent that
> >> others might copy by mistake.
> >> 
> >> As we need to change stats code to do byteswaps for virtio 1.0, it seems easy
> >> to fix by prepending a 6 byte reserved field.  I also had to change config
> >> structure field types from __le32 to __u32 to match other devices. This means
> >> we need a couple of __force tags for legacy path but that seems minor.
> >
> > Rusty, what are your thoughts here?
> > How about merging this for 4.1?
> 
> I disagree with making any changes, other than allowing it to be used
> with VIRTIO_F_VERSION_1.
> 
> However it doesn't seem to bother anyone else, so I've applied it for
> 4.1.

I'm still not really convinced about the stats change either, FWIW.
Still time to reconsider? And should we perhaps wait with merging until
the spec change allowing version 1 has been accepted?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/